Saturday, December 19, 2009

'Fantastic Fixed Gear Calculator!'



There's tons of different types of gearing calculators out there, some good, some maybe less so.

Here's yet another one, SURPLACE Fantastic Fixed Gear Calculator! which actually looks pretty fantastic to me. I like especially the equivalent gear table which many other calculators miss. Check it out!

Plus thanks to Otto for pointing this out for me.

2 comments:

blair said...

this calculator is WRONG. do not use it.

two things are wrong -- one, if you click "ambidextrous skidder," it simply doubles the number of skid patches on your wheel. that's not how it works. some gear combos do NOT double when you're ambidextrous, such as 42x15.

secondly, the "equivalent gear" table will provide you with gear ratios that are CLOSE to what you run, but not EXACT. in fact, sometimes they can be off by as much as 2 or 3 gear inches.

DO NOT SUPPORT THIS CALCULATOR, IT LIES.

bozze said...

Does not agree with you, I don't think it lies, just read the thread linked in the about section.
Additionaly, here is what I responded to pedal consumption when they asked to me why I changed the skid patch calculation method :

Hi Patrick,

You are right, after I posted the Calculator, some people started to
discuss about the method to calculate skid patch number for an ambidextrous
skidder, on www.pignonfixe.com (the french main forum).

I based my method on the Sheldon Brown site, but his site contains errors
and contradiction (I know, what a blasphemy!):

1)

" If you are an ambidextrous skidder, and the simplified ratio has
an even numerator or denominator, your number of skid patches will
be the same.

If you are an ambidextrous skidder, and both the numerator and
denominator are odd, the number of possible skid patches will be
doubled. "

2)

" If you are an ambidextrous skidder, and the calculation gives an
even result, your number of skid patches will be the same.

If you are an ambidextrous skidder, and have an odd denominator,
the number of possible skid patches will be doubled."

It's a subtle difference but that change the final result.
To stop the debate, someone on the forum tried to demonstrate mathematicaly
what are the conditions that doubles the number of skid patch, here:



I'm not good enough at mathematics, so I only can believe it and here are
the 2 resulting rules/facts :

1) The denominator of the simplified fraction (of the gear ratio) is the
number of skid patches

2) If you are an ambidextrous skidder and have an ODD NUMERATOR in the
simplified fraction, the number of possible skid patches will be doubled if